Coarse sea salt
1 pound cavatappi
1 quart milk
1 stick unsalted butter
1/2 cup flour
12 ounces Gruyere, grated (4 cups)
8 ounces extra-sharp Cheddar, grated (2 cups)
1/2 teaspoon black pepper
1/2 teaspoon ground nutmeg
3/4 pound fresh tomatoes (4 small)
1 1/2 cups fresh white bread crumbs (5 slices, crusts removed)
Preheat the oven to 375 degrees F
Boil a large pot of salted water. Add the cavatappi and cook to al dente. Drain well.
Meanwhile, heat the milk in a small saucepan, but don’t boil it. Melt butter in a large pot and add the flour. Cook over low heat for 2 minutes, stirring with a whisk. While whisking, add the hot milk and cook for a minute or two more, until thickened and smooth. Off the heat, add the Gruyere, Cheddar, 1 tablespoon salt, pepper, and nutmeg. Add the cooked macaroni and stir well. Pour into a 3-quart baking dish.
Slice the tomatoes and arrange on top. Melt the remaining 2 tablespoons of butter, combine them with the fresh bread crumbs, and sprinkle on the top. Bake for 30 to 35 minutes, or until the sauce is bubbly and the macaroni is browned on the top.